This invention relates to an improved frame construction for self-supporting spherical enclosures, and is particularly concerned with self-supporting structures of the type commonly referred to as "radomes."
A self-supporting radome construction is disclosed in U.S. Pat. No. 3,392,495. In that disclosed structure, a random distribution of structural elements is provided which employs a limited number of different-sized structural components without adversely affecting the performance of radar equipment enclosed therein. Further, that structure provides for a random distribution of structural elements or struts being divided into four basic groups. A typical structure in accordance with U.S. Pat. No. 3,392,495 was nineteen panels per section and twenty triangular sections per dome. Further, where the inner surface of the radome differs from the outer surface a maximum of five different panels are required, because although only four basic panel groups are required, one of the groups is unequally shaped and two sets must therefore be provided, one the mirror image of the other.
The present invention provides a radome construction which is an improvement of the radome construction disclosed in U.S. Pat. No. 3,392,495. Our invention decreases the number of individual panels required, the kinds of panels and the number of structural elements or struts. This results in reduced manufacturing, shipping, and erection costs.
More particularly, in the aforementioned patent where the exterior finish is different than the interior finish, five basic size panels are required for construction. With the present inventionn, only four panel sizes are necessary regardless of the surface finish required. In the present invention, the configuration of panels also results in fewer panels required for each triangular area.
In the preferred embodiment of the invention, four basic triangular openings are formed utilizing four basic elements. The triangular openings are interconnected in a standard reoccurring pattern. Each pattern comprises three first isosceles triangles, three equilateral triangles, three second isosceles triangles, a fourth equilateral triangle and three identical irregular triangles.
Each of the first isosceles triangles has a vertex located at one of the vertices of an imaginary spherical triangular subdivision. One side of each of the three equilateral triangles is equal and parallel to the base of each of the first isosceles triangles. The vertices of the fourth equilateral triangle are common to a vertex of each of the three equilateral triangles.
The three second isosceles triangles each have one side equal and parallel to one side of the three equilateral triangles and the other side equal and parallel to one side of the fourth equilateral triangle.
The three identical irregular triangles each have a side extending from the common vertices of the three equilateral triangles and the fourth equilateral triangle, which side extends through an equal distance beyond the sides of the imaginary triangular subdivision. Another side is equal and parallel to a side of each of the three equilateral triangles.